2km海拔下直流线路金具起晕场强预测修正方法

Prediction Method of Corona Inception Field Intensity for HVDC Line Fittings at 2 km Altitude

起晕场强是输电线路金具设计的重要依据,目前高海拔地区直流输电线路金具设计依据的Peek公式是基于低海拔下曲率半径在50 mm以内的细导线电晕放电试验结果获得的。±800 kV直流输电线路金具属于大曲率半径(大于100 mm,下同)和三维结构电极结构,其与细导线结构电极的放电机理不同,因此Peek公式已不再适用于此类直流输电线路金具设计,尤其是高海拔地区直流线路金具的设计。本文针对Peek公式对于大曲率半径和非圆柱体电极起晕场强预测不准确问题,利用海拔2 100 m下昆明特高压试验室搭建的真型直流线路金具试验平台,对模拟金具管和均压环的起晕电压进行了测试。基于起晕场强和曲率半径的关系,首次提出了基于高斯曲率的大曲率半径直流金具电极的起晕场强计算公式的修正方法,为相应海拔地区的特高压直流线路金具设计提供了理论依据。

Corona inception field strength is one of the important parameters for the design of fittings in ± 800 k V DC transmission line. So far Peek formula is still the basis for the prediction of corona inception field strength of DC line fittings with large size at high altitude area. Peek formula was obtained by experimental results of electrode with curvature radius less than 50 mm at standard atmospheric pressure. Because the discharge mechanism of the electrode with large curvature radius（ larger than 100 mm,hereafter the same） and 3D structure is different,Peek formula is inaccurate for predicting the corona inception field strength for this kind of electrode,especially at high altitude area. In order to predict the corona inception field strength of the fittings with larger curvature radius and non-cylinder structure accuratly,a test platform for HVDC fittings is set up in Kunming high voltage laboratory at 2 100 m altitude. Corona inception voltages are measured for test tubes and rings in the lab. Correction method to Peek formula is proposed firstly for the electrode with larger curvature and 3D structure at high altitude area. This method will become one of the theory evidences for the design of HVDC fittings at 2 km altitude area.